Modern motor vehicles driven by an internal combustion engine have, associated with them, a generator which is used to supply power for electrical current-consuming equipment, such as for example, lights, a radio, power windows, etc. In addition, a battery is provided to insure that sufficient power is available in times of peak power demand. Accordingly, the battery must be recharged periodically. Recharging is especially necessary after the battery is used to power the starter during the engine start -up procedure. The energy required for recharging the battery increases the fuel consumption of the motor vehicle.
Japanese patent abstract Volume 10, No. 381 (M-547) (2438) and JP-A-61-171839 disclose a method for controlling the generator associated with an internal combustion engine, wherein the generator is operated only during specific operating conditions of the internal combustion engine. Specifically, the generator is operated only when a "partial-lean control" cannot be effected.
French Patent document FR-A 2 495 384 discloses a vehicle battery charging circuit having a detector and a switch for selectively coupling/decoupling a generator (which is used for charging the battery) in accordance with either the charge state of the battery or predetermined engine operating conditions. Once the battery is fully charged, the detector generates an interrupt in the circuit. The interrupt shuts off the generator output to the battery thereby reducing the power taken by the generator which, in turn, improves the average efficiency of the engine. The switch is coupled to the throttle pedal in a manner such that the generator is permitted to charge the battery only at low throttle openings.
In spite of the methods and apparatus for controlling the operation of a generator disclosed in the prior art, there still remains a need to further reduce the total fuel consumption required to generate electrical energy in a motor vehicle.